Low-stress and flat sheets optimize processingwith minimum stress Leading European metalworking company chooses Kohler 85P.2000 part leveling machine

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Cutting, punching, edge trimming, bending, milling, turning, welding, assembling: At every stage of sheet metal processing, stresses in the sheets sometimes play a major role in determining how smoothly the production process runs. These stresses, combined with how flat the blanks are, have a significant impact on productivity and quality when manufacturing edged and bent parts, as well as in the production of welded assemblies.Leveled sheets, by contrast, exhibit little stress and have the required degree of flatness to be processed further without any problems.

These advantages are appreciated by EKO MEĐIMURJE d.d., which is based in Croatia and mainly produces complex sheet metal constructions. Whether cabs or tanks for mining machinery from well-known brands such as Liebherr, Komatsu and Caterpillar, or ovens for the food industry —time-consuming rework, distortion when welding, and inconsistent results are a thing of the past, since the introduction of Kohler part leveling machines.

EKO MEĐIMURJE d.d. has around 400 employees and processes approximately 500 tons of steel a month. Its production site covers 20,000 m² and boasts modern machinery: Laser machines, diverse plasma cutting systems and press brakes, plus 110 welding machines, two robot welding stations, Cobot welding robot, numerous machining centers and modern paintshop form the backbone of the production process. To improve quality and significantly shorten throughput times, the production line has recently been expanded with the addition of a Peak Performer 85P.2000 part leveling machine from Kohler Maschinenbau GmbH.

Leveling: Precision right from the get-go

The leveling of sheet metal on a roll leveling machine is nothing more than a series of repeated bending operations. During this process, the material is subjected to ever decreasing alternating bending generated by offset leveling rollers. Imagine the bending process as a decaying sine curve. As the material passes through the first leveling rollers, it is subjected to strong alternating bending, which becomes weaker as leveling progresses. Finally, the curvature and bending are reduced to the extent that the sheet adopts a flat state without any additional springback. The alternating bending and continuous decrease in forming means that after leveling, the material is, for all intents and purposes, stress-free. Areas of the material that were previously under stress are elongated and compressed around the neutral axis beyond the yield point to achieve the desired level of stress reduction.

Stress-free leveling for ultra-precise welded constructions

"We supply customers who are primarily based within Europe. They demand top quality of delivered products. At the same time, the quality of purchased sheet plates, in terms of flatness and without internal stress, can only be expected up to limited degree which is not enough for the process.The highest levels of precision have to be ensured in the manufacture of our steel assemblies, whether they're cabs, tanks or different machine parts. The largest product we've ever produced had, believe it or not, a total weight of  74 tons. When welding, however, we were only able to achieve the desired level of flatness in the past with a great deal of trouble. Vast amounts of production-related activities and much manual work was necessary. We frequently employed specialists who leveled the parts using a torch before they could be welded with the required degree of precision into assemblies that in some cases weighed several tons. In many cases the results were satisfactory, though they were not always to a consistent standard and, more significantly, could not be achieved in a way that met our productivity targets.

We eventually came across Kohler through our friends at Karmet Bulgaria LTD. Karmet is a close trading partner of Kohler and was able to show us a machine that precisely met our requirements. We then submitted some of our key parts to extensive leveling trials at the well-equipped KOHLER leveling center. These parts were then fed back into our production lines. We were able to see right away the massive increase in quality and productivity that the leveled parts gave us in the subsequent bending and welding operations. This clearly showed us that this investment would be key to the ongoing development of our company. After placing our order and its seamless processing, the Peak Performer 85P.2000 part leveling machine was successfully up and running on our site by the end of 2023. The introduction of the KOHLER part leveling machine has enabled us to reduce to a minimum the amount of alignment work the sheets require before welding. Likewise, there's now less distortion during the welding process," explained Zoran Zdolec, Electrical Facilities Manager at EKO MEĐIMURJE d.d.

Maximum cost-effectiveness thanks to innovative features & functions

The regular cleaning of particles of dirt from the leveling rollers and supporting rollers is essential, particularly when working with up to 90% blackplate.The user-friendliness of ACS, the advanced cleaning system only available in this performance category from KOHLER, also made a big impression on EKO.

Weekly cleaning with the advanced cleaning system is more or less child's play. Cleaning prevents the accumulation of deposits on the leveling rollers and supporting rollers, as well as on the leveling material itself. "The fully retractable leveling cassette enables all the rollers to be cleaned quickly and easily. This extra feature not only improves our leveling results by eliminating contamination, it also considerably extends the service life of the rollers", pointed out Zoran Zdolec.

Intuitive operating concept & high levels of energy efficiency

The ease of operation of the KOHLER Peak Performer 85P.2000 part leveling machine also impressed the Croatian sheet metal specialists. The HMI and the Expert Calculation System tool, which is installed as standard, are of such a simple and intuitive design that the operator can quickly locate the appropriate material-specific parameters. Presaved settings for known parts can also be accessed quickly, making the whole process much more straightforward. Last but not least, EKO was also won over by Kohler’s advanced environmental credentials. The Peak Performer 85P.2000 is not only powerful, it's also energy-efficient, and hence environmentally friendly as well. All Kohler part leveling machines work without hydraulics, so are therefore noticeably superior to conventional levelers. The results across the entire range of materials were, without exception, outstanding: Leveling with low levels of maintenance, no leakages, no susceptibility to the high temperatures prevailing in Croatia, greater energy efficiency and hence improved environmental sustainability.

"The low electricity consumption is extremely welcome. In stand-by mode, the Kohler part leveling machine uses under 2 KW, while in idle, consumption increases to just about 2.5 KW. Apart from the electromechanical dynamic gap control, this low consumption is down to the fact that the individual leveling rollers are all direct drive rollers. The electromechanical dynamic gap control, a patented Kohler feature, ensures superb leveling results, even with complex geometries. The direct drive system uses a separate drive for each leveling roller. The result of this is that individual drives, fitted with planetary gearing, are used in preference to a large distribution gear with an oversized central drive.

All things considered, we are extremely satisfied. That demonstrates that the investment decision was the right one! The part leveling machine will have paid for itself in very reasonable time," concluded Zoran Zdolec.

Part leveling machine at EKO MEĐIMURJE d.d.:

• Peak Performer 85P.2000

• The leveled sheets are primarily of blackplate

• Width of the sheets: up to 2,000 mm

• Material thickness of the sheets: up to 28 mm

• Advanced cleaning system

• Patented electromechanical dynamic gap control

• Intelligent overload protection

• Pinch-off edge protection

• Easy-Feed

• Direct drive

• Intuitive user interface

The advanced environmental credentials of Kohler part leveling machines:

Powerful and energy-efficient at the same time—and environmentally friendly as well

• Servo-electronic machine concept without any hydraulics

• From size 60P: responsive, electromechanical dynamic gap control

• From size 85P: energy-efficient and powerful direct drives